I was grocery shopping a while back, beefing up the larder for our son's visit. David attends college back east, Cornell University to be precise. I rarely see him anymore, except when he can dig himself free of snowdrifts. When he visits, he's the only one in Southern California to rejoice Santa Ana conditions.

When David is in town, I stock the refrigerator with three types of milk - 2% for my husband, Lactaid for myself, and skim for him. A tiny clarification is required here. David isn't really related to my husband, but they are as close as any father and son ought to be.

As I reached for David's skim milk, and as is customary when buying anything these days, I checked the expiration date. I paused, incredulous at first, then dismayed. I blinked back tears as I stood in the dairy section, other shoppers gaily cruised by. The expiration date on David's milk carton was going to outlast his visit. Though he planned to be home for ten days, his skim milk was going to be with us an extra five - presuming it would last that long. The length of my son's visit suddenly had a shelf life shorter than his milk! And good heavens, my Lactaid was destined to be around for two months. Mothers think this way. Ask any mother. We count from the moment a child is born - starting with their toes.

Not wanting the milk to sour my anticipation of his arrival, I decided to make a game of it - to determine the length of time the items on my list were going to visit - maybe even still be with us when David plans to visit next summer. I shed my sadness and started to hum to the corny piped-in tunes sailing down the aisles. I suddenly felt as quippy and clever as Andy Rooney.

I peered through my trifocals (David is what one calls a late-in-life planned bonus), scanned my list and started to pluck items from the shelves, cases and bins. The flour would clearly be with us longer than David - I don't bake when he's not home. The snap beans were planning a one night stand, the brisket would linger for a week, and the apple cider was staging a cameo. The bagels, cashews, dill dip mix, and carrot sticks would hang around about the same amount of time as he. This was good.

By the time my cart was filled, my itemized list complete - plus the $50 worth of extras I discovered - my head was full of numbers from gauging the groceries according to the length of time David would be with us. It was insane.

It had all started with the milk, perhaps a soppy metaphor of David's first nourishment the day he was born. I leaned into my cart and lifted out the skim milk carton, patted it, and said, "That's all right, you stay as long as you want." It was entirely insane, but ask any mother. We are insane. Yet, I'm lucky. For all the numbers that have filled my head over the years, I have lost count of the number of times we have told each other "I love you."

Several days after David left, I was banging around my kitchen cupboards and noticed he hadn't eaten the Mega Noodle Chicken Soup I had especially bought for him. Not to worry, I sighed, it would happily await his return. And so would I, because a mother's love has no expiration date.